Epic Systems Corporation is located on an 811-acre site in rural Wisconsin. The latest addition to Epic's campus is a 1.2-million-square-foot underground auditorium. Thornton Tomasetti provided structural design, building skin and construction support services—which included consulting on building envelope systems and a fully detailed Tekla model—for the 11,400-seat auditorium, with the ability to expand to 14,000 seats.
Excavated into a hillside to preserve views throughout the campus, the auditorium extends 74 feet underground and is covered by an eight-acre green roof. The column-free roof is supported by 25-foot-deep trusses spanning 275 feet. The long-span roof was one of the project’s most challenging components. Unique load considerations, including soil and gravel depths of up to 16 inches, and erection issues had a strong influence on the roof structure's design. To ensure an efficient structure and limit potential conflicts during construction, the company consulted on erection engineering and design for the 4,200-ton roof lift. The roof trusses were specially designed to accommodate erecting the structure on the ground and strand jacking the entire roof into position.